U.S. patent application number 16/994916 was filed with the patent office on 2021-03-11 for impact absorption device.
This patent application is currently assigned to AISIN SEIKI KABUSHIKI KAISHA. The applicant listed for this patent is AISIN KEIKINZOKU KABUSHIKI KAISHA, AISIN SEIKI KABUSHIKI KAISHA. Invention is credited to Kiyoichi KITA, Syunji MORI, Shunji SHIBATA, Jun SYOBO, Kenji TAMAKI, Masaaki YOSHIMURA.
Application Number | 20210070370 16/994916 |
Document ID | / |
Family ID | 1000005029981 |
Filed Date | 2021-03-11 |
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United States Patent
Application |
20210070370 |
Kind Code |
A1 |
MORI; Syunji ; et
al. |
March 11, 2021 |
IMPACT ABSORPTION DEVICE
Abstract
An impact absorption device includes: a pair of an upper wall
portion and a lower wall portion extending in the vehicle
front-rear direction and placed to face each other; and a plurality
of ribs extending in the vehicle front-rear direction between the
upper wall portion and the lower wall portion, the ribs being
arranged at predetermined intervals in the vehicle width direction
so as to divide a space between the upper wall portion and the
lower wall portion into a plurality of sections extending in the
vehicle front-rear direction. Among the sections, three consecutive
sections in an arrangement direction of the sections are configured
such that an interval between ribs constituting a central section
in the arrangement direction is smaller than an interval between
ribs constituting each of sections adjacently placed on both sides
of the central section.
Inventors: |
MORI; Syunji; (Kariya-shi,
JP) ; SHIBATA; Shunji; (Kariya-shi, JP) ;
YOSHIMURA; Masaaki; (Kariya-shi, JP) ; TAMAKI;
Kenji; (Kariya-shi, JP) ; KITA; Kiyoichi;
(Okazaki-shi, JP) ; SYOBO; Jun; (Anjo-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AISIN SEIKI KABUSHIKI KAISHA
AISIN KEIKINZOKU KABUSHIKI KAISHA |
Kariya-shi
Imizu-shi |
|
JP
JP |
|
|
Assignee: |
AISIN SEIKI KABUSHIKI
KAISHA
Kariya-shi
JP
AISIN KEIKINZOKU KABUSHIKI KAISHA
Imizu-shi
JP
|
Family ID: |
1000005029981 |
Appl. No.: |
16/994916 |
Filed: |
August 17, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B62D 21/157 20130101;
B62D 25/20 20130101 |
International
Class: |
B62D 21/15 20060101
B62D021/15; B62D 25/20 20060101 B62D025/20 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 5, 2019 |
JP |
2019-161731 |
Claims
1. An impact absorption device for absorbing a collision energy by
deforming when an object collides with a side part of a vehicle
from a lateral side of the vehicle toward a central part side of
the vehicle in a vehicle width direction, the impact absorption
device comprising: a pair of an upper wall portion and a lower wall
portion extending in a vehicle front-rear direction in the side
part of the vehicle, the upper wall portion and the lower wall
portion being distanced from each other in a vehicle height
direction and placed to face each other; and a plurality of ribs
extending in the vehicle front-rear direction between the upper
wall portion and the lower wall portion, the ribs being arranged at
predetermined intervals in the vehicle width direction so as to
divide a space between the upper wall portion and the lower wall
portion into a plurality of sections extending in the vehicle
front-rear direction, wherein, among the sections, three
consecutive sections in an arrangement direction of the sections
are configured such that an interval between ribs constituting a
central section in the arrangement direction is smaller than an
interval between ribs constituting each of sections adjacently
placed on both sides of the central section.
2. The impact absorption device according to claim 1, wherein an
interval between ribs constituting one given section in a part
adjacently placed on either side of the three consecutive sections
among the sections is equal to or more than an interval between
ribs constituting an adjacent section adjacently placed on a
reverse side of the one given section in an advancing direction of
the object.
3. The impact absorption device according to claim 1, wherein the
number of sections placed on a forward side, in an advancing
direction of the object, from a rib placed on a reverse side in the
advancing direction of the object out of two ribs constituting the
central section is an odd number.
4. The impact absorption device according to claim 1, wherein the
upper wall portion and the lower wall portion are placed in
parallel to each other.
5. The impact absorption device according to claim 1, wherein an
interval, in the vehicle height direction, between first end parts
of the upper wall portion and the lower wall portion is smaller
than an interval, in the vehicle height direction, between second
end parts of the upper wall portion and the lower wall portion, the
first end parts being placed on a reverse side in an advancing
direction of the object, the second end parts being placed on a
forward side in the advancing direction of the object.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Japanese Patent
Application No. 2019-filed on Sep. 5, 2019, incorporated herein by
reference in its entirety.
BACKGROUND
1. Technical Field
[0002] The present disclosure relates to an impact absorption
device for a vehicle. Particularly, the present disclosure relates
to an impact absorption device configured to absorb an impact
applied to a side part of a vehicle.
2. Description of Related Art
[0003] For example, as described in Japanese Unexamined Patent
Application Publication No. 2018-90021 (JP 2018-90021 A), there has
been known an impact absorption device configured to absorb a
collision energy when an object collides with a side part of a
vehicle. The impact absorption device includes an upper wall
portion and a lower wall portion extending in the vehicle
front-rear direction below a doorway of the vehicle. The upper wall
portion and the lower wall portion are distanced from each other in
the vehicle height direction. The upper wall portion and the lower
wall portion are placed so that their plate-thickness directions
are along the vehicle height direction. A plurality of ribs is
provided between the upper wall portion and the lower wall portion.
A space between the upper wall portion and the lower wall portion
is divided into a plurality of sections by the ribs. The width of
each section (the interval between ribs) decreases as it goes from
an end part side of the vehicle in the vehicle width direction to a
central part side of the vehicle. In the meantime, as illustrated
in FIG. 11, such an impact absorption device 1A has been known that
the width of a section D.sub.n+1 (the interval between a rib
R.sub.n+1, and a rib R.sub.n+2) is equal to or more than the width
of a section D.sub.n (the interval between a rib R.sub.n and the
rib R.sub.n+1).
[0004] When an object collides with a side part of a vehicle to
which the impact absorption device 1A is applied, and the object
presses the impact absorption device 1A to a central part side of a
vehicle body in the vehicle width direction, the impact absorption
device 1A deforms to be compressed in the vehicle width direction.
That is, parts of the upper wall portion and the lower wall portion
constituting the impact absorption device 1A buckle, the parts
being placed between the ribs, so that the impact absorption device
1A deforms in a bellows manner. Hereby, a collision energy of the
object is absorbed (see FIGS. 13, 14).
SUMMARY
[0005] In a case where an application direction of a pressing load
to the impact absorption device 1A is parallel to an arrangement
direction (the vehicle width direction) of the sections (see a
first experiment in FIGS. 13, 14), the impact absorption device 1A
deforms in a bellows manner as described above, so that the
collision energy is absorbed efficiently. In the meantime, in a
case where the application direction of the pressing load to the
impact absorption device 1A is inclined from the arrangement
direction (the vehicle width direction) of the sections (the
application direction is directed diagonally downward (a second
experiment in FIGS. 13, 14)), the impact absorption device 1A
deforms to collapse downward (see FIG. 12). In this case, the upper
wall portion partially remains without buckling, so that the
collision energy may not be sufficiently absorbed (see FIGS. 13,
14).
[0006] The present disclosure provides an impact absorption device
having improved collision-energy absorption performance. Note that,
in the following description of each constituent feature of the
present disclosure, a reference sign of a corresponding portion in
an embodiment is described within a parenthesis to facilitate
understanding of the present disclosure. However, the constituent
features of the present disclosure should not be construed
limitatively to a configuration of the corresponding portion
indicated by the reference sign in the embodiment.
[0007] An impact absorption device according to an aspect of the
present disclosure is an impact absorption device for absorbing a
collision energy by deforming when an object collides with a side
part of a vehicle from a lateral side of the vehicle toward a
central part side of the vehicle in the vehicle width direction.
The impact absorption device includes a pair of an upper wall
portion and a lower wall portion, and a plurality of ribs. The
upper wall portion and the lower wall portion extend in the vehicle
front-rear direction in the side part of the vehicle. The upper
wall portion and the lower wall portion are distanced from each
other in the vehicle height direction and placed to face each
other. The ribs extend in the vehicle front-rear direction between
the upper wall portion and the lower wall portion. The ribs are
arranged at predetermined intervals in the vehicle width direction
so as to divide a space between the upper wall portion and the
lower wall portion into a plurality of sections extending in the
vehicle front-rear direction. Among the sections, three consecutive
sections in an arrangement direction of the sections are configured
such that an interval between ribs constituting a central section
in the arrangement direction is smaller than an interval between
ribs constituting each of sections adjacently placed on both sides
of the central section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Features, advantages, and technical and industrial
significance of exemplary embodiments of the disclosure will be
described below with reference to the accompanying drawings, in
which like signs denote like elements, and wherein:
[0009] FIG. 1 is a plan view of a vehicle to which an impact
absorption device according to one embodiment of the present
disclosure is applied;
[0010] FIG. 2 is a perspective view of the impact absorption device
in FIG. 1:
[0011] FIG. 3 is a front view illustrating a collision form of an
object in a first experiment;
[0012] FIG. 4 is a schematic view illustrating a principle that an
upper wall portion and a lower wall portion deform to outside or
inside of a section;
[0013] FIG. 5A is a schematic view illustrating an outline of a
deformation form of the impact absorption device in the first
experiment;
[0014] FIG. 5B is a schematic view illustrating the outline of the
deformation form of the impact absorption device in the first
experiment;
[0015] FIG. 5C is a schematic view illustrating the outline of the
deformation form of the impact absorption device in the first
experiment;
[0016] FIG. 5D is a schematic view illustrating the outline of the
deformation form of the impact absorption device in the first
experiment:
[0017] FIG. 6 is a front view illustrating a collision from of an
object in a second experiment;
[0018] FIG. 7A is a schematic view illustrating an outline of a
deformation form of the impact absorption device in the second
experiment;
[0019] FIG. 7B is a schematic view illustrating the outline of the
deformation form of the impact absorption device in the second
experiment;
[0020] FIG. 7C is a schematic view illustrating the outline of the
deformation form of the impact absorption device in the second
experiment;
[0021] FIG. 7D is a schematic view illustrating the outline of the
deformation form of the impact absorption device in the second
experiment;
[0022] FIG. 8 is a graph illustrating changes of a compressive load
in the first experiment and the second experiment;
[0023] FIG. 9 is a graph illustrating changes of an impact
absorption amount (a collision energy absorption amount) in the
first experiment and the second experiment;
[0024] FIG. 10 is a front view of an impact absorption device
according to a modification of the present disclosure;
[0025] FIG. 11 is a front view of an impact absorption device in a
related art:
[0026] FIG. 12 is a schematic view illustrating an outline of a
deformation form, in the second experiment, of the impact
absorption device in the related art:
[0027] FIG. 13 is a graph illustrating changes of a compressive
load in the first experiment and the second experiment in the
impact absorption device in the related art; and
[0028] FIG. 14 is a graph illustrating changes of an impact
absorption amount (a collision energy absorption amount) in the
first experiment and the second experiment in the impact absorption
device in the related art.
DETAILED DESCRIPTION OF EMBODIMENTS
[0029] An impact absorption device 1 according to an embodiment of
the present disclosure will be described below. As illustrated in
FIG. 1, the impact absorption device 1 is provided in each side
part of a vehicle V such that the impact absorption device 1 is
placed below a floor panel constituting a floor face of a vehicle
cabin.
[0030] When an object OB (e.g., a columnar object extending in a
vertical direction (see FIG. 3)) collides with a side part of the
vehicle V from a lateral side of the vehicle V, the impact
absorption device 1 is pressed by the object OB to a central part
side of the vehicle V in the vehicle width direction. Hereby, the
impact absorption device 1 deforms, so that a collision energy of
the object OB is absorbed. An entry amount of a member constituting
the side part of the vehicle V to the vehicle cabin is reduced by
such an impact absorption function.
[0031] The impact absorption device 1 provided in a left side part
of the vehicle V and the impact absorption device 1 provided in a
right side part of the vehicle V have a symmetric shape in the
right-left direction, and their other configurations are the same.
In view of this, the following deals with the impact absorption
device 1 provided in the left side part of the vehicle V, and the
impact absorption device 1 provided in the right side part is not
described herein.
[0032] As illustrated in FIG. 2, the impact absorption device 1
extends in the vehicle front-rear direction. The impact absorption
device 1 is an extruded molded product formed integrally by
extrusion of an aluminum material. The impact absorption device 1
has a tubular shape extending in the vehicle front-rear direction.
The impact absorption device 1 is assembled to the vehicle V such
that the extrusion direction of the aluminum material is along the
vehicle front-rear direction.
[0033] As illustrated in FIG. 3, the impact absorption device 1
includes an upper wall portion U and a lower wall portion L. The
upper wall portion U and the lower wall portion L are
band-plate-shaped parts extending in the vehicle front-rear
direction. The upper wall portion U and the lower wall portion L
are placed such that their plate-thickness directions are along the
vehicle height direction. The upper wall portion U and the lower
wall portion L are distanced from each other in the vehicle height
direction and are placed to face each other. A left end and a right
end of the upper wall portion U are placed right above a left end
and a right end of the lower wall portion L, respectively. The
plate thickness of the upper wall portion U is equal to the plate
thickness of the lower wall portion L.
[0034] Ribs R.sub.1 to R.sub.9 are provided between the upper wall
portion U and the lower wall portion L. The ribs R.sub.1 to R.sub.9
are band-plate-shaped parts extending in the vehicle front-rear
direction. Respective plate thicknesses of the ribs R.sub.1 to
R.sub.9 are equal to the plate thickness of the upper wall portion
U (the plate thickness of the lower wall portion L). The ribs
R.sub.1 to R.sub.9 are placed such that their plate-thickness
directions are along the vehicle width direction. First end parts,
in the width direction (the vehicle height direction), of the ribs
R.sub.1 to R.sub.9 are connected to a bottom face of the upper wall
portion U, and second end parts, in the width direction, of the
ribs R.sub.1 to R.sub.9 are connected to an upper face of the lower
wall portion L.
[0035] The rib R.sub.1 is placed in the left ends of the upper wall
portion U and the lower wall portion L. Further, the rib R.sub.9 is
placed in the right ends of the upper wall portion U and the lower
wall portion L. The ribs R.sub.2 to R.sub.8 are placed in this
order at predetermined intervals as described below between the rib
R.sub.1 and the rib R.sub.9. Hereby, a space between the upper wall
portion U and the lower wall portion L is divided into eight
sections D.sub.1 to D.sub.8. That is, a part between a rib R.sub.n
(=.sub.1, 2, . . . , 8) and a rib R.sub.n+1 corresponds to a
section Dn. In the following description, a "width d.sub.n of the
section D.sub.n" indicates an interval (a distance in the vehicle
width direction) between the rib R.sub.n and the rib R.sub.n+1
constituting the section D.sub.n. Further, a part, of the upper
wall portion U, that constitutes the section D.sub.n (that is, a
part between the rib R.sub.n and the rib R.sub.n+1) is referred to
as an upper wall portion U.sub.n. Further, a part, of the lower
wall portion L, that constitutes the section D.sub.n (that is, a
part between the rib R.sub.n and the rib R.sub.n+1) is referred to
as a lower wall portion L.sub.n.
[0036] A width d.sub.1 of the section D.sub.1, a width d.sub.2 of
the section D.sub.2, and a width d.sub.3 of the section D.sub.3 are
the same. A width da of the section D.sub.4 is slightly larger than
the width d.sub.3 of the section D.sub.3, and a width d.sub.5 of
the section D.sub.5 is further larger than the width d.sub.4 of the
section D.sub.4. A width d.sub.6 of the section D.sub.6 is smaller
than the width d.sub.5 of the section D.sub.5. A width d.sub.7 of
the section D.sub.7 is larger than the width d.sub.6 of the section
D.sub.6, and a width d.sub.8 of the section D.sub.8 is further
larger than the width d.sub.7 of the section D.sub.7. More
specifically, the widths d.sub.1 to d.sub.8 are set as illustrated
in Table 1.
TABLE-US-00001 TABLE 1 d.sub.1 d.sub.2 d.sub.3 d.sub.4 d.sub.5
d.sub.6 d.sub.7 d.sub.8 3 mm 3 mm 3 mm 22.1 mm 27.2 mm 22.1 mm 33.2
mm 44.2 mm
[0037] Next will be described results (simulation results) of a
first experiment and a second experiment about collision-energy
absorption performance of the impact absorption device 1.
Result of First Experiment
[0038] In the first experiment, a columnar object OB was caused to
collide, from the left side, with a central part of the impact
absorption device 1 in the vehicle front-rear direction (see FIG.
3). Note that the object OB extends in the vertical direction and
slides from the left side to the right side of the vehicle V. When
the widths d.sub.1 to d.sub.8 were set as illustrated in Table 1,
the sections D.sub.1 to D.sub.8 were crushed in this order as
described below.
[0039] The following describes deformation forms (crush forms of
the sections D.sub.1 to D.sub.8) of the impact absorption device 1.
The object OB abuts with a left end face (a left surface of the rib
R.sub.1) of the impact absorption device 1. Since the object OB has
a columnar shape as described above, a pressing load is
concentratedly applied to a linear part extending in the vehicle
height direction, the linear part being an abutment part between
the rib R.sub.1 and the object OB. Here, the upper wall portion U
and the lower wall portion L are connected to an upper end part and
a lower end part of the rib R.sub.1 in the vehicle height
direction, respectively, and therefore, respective strengths of the
upper end part and the lower end part of the rib R.sub.1 are higher
than a strength of an intermediate part of the rib R.sub.1 in the
vehicle height direction. On this account, the intermediate part of
the rib R.sub.1 first bends slightly to the right side. As a
result, apart (a left half part), of an upper wall portion U.sub.1,
that is placed on the left side from a central part of the upper
wall portion U.sub.1 deforms to rotate counterclockwise in the
figure around a connecting portion UR.sub.1 between the rib R.sub.1
and the upper wall portion U. Further, a part (a right half part),
of the upper wall portion U.sub.1, that is placed on the right side
from the central part of the upper wall portion U.sub.1 deforms to
rotate clockwise in the figure around a connecting portion UR.sub.2
between the rib R.sub.2 and the upper wall portion U. In the
meantime, a part (a left half part), of a lower wall portion
L.sub.1, that is placed on the left side from a central part of the
lower wall portion L.sub.1 deforms to rotate clockwise in the
figure around a connecting portion LR.sub.1 between the rib R.sub.1
and the lower wall portion L. Further, apart (a right half part),
of the lower wall portion L.sub.1, that is placed on the right side
from the central part of the lower wall portion L.sub.1 deforms to
rotate counterclockwise in the figure around a connecting portion
LR.sub.2 between the rib R.sub.2 and the lower wall portion L. As
such, an intermediate part of the upper wall portion U.sub.1
buckles to project upward, and an intermediate part of the lower
wall portion L.sub.1 buckles to project downward.
[0040] When buckling of the upper wall portion U.sub.1 and the
lower wall portion L.sub.1 progresses, and the section D.sub.1 is
completely crushed, so that the rib R.sub.1 abuts with the rib
R.sub.2, the rib R.sub.2 starts to be pressed to the right side. As
described above, the right half part of the upper wall portion
U.sub.1 rotates clockwise in FIG. 4 around the connecting portion
UR.sub.2, and the right half part of the lower wall portion L.sub.1
rotates counterclockwise in the figure around the connecting
portion LR.sub.2. As a counteraction of a load causing such
deformations, a load directed diagonally downward toward the left
side is applied to a left half part of an upper wall portion
U.sub.2, and a load directed diagonally upward to the left side is
applied to a left half part of a lower wall portion L.sub.2.
Hereby, the upper wall portion U.sub.2 and the lower wall portion
L.sub.2 buckle to be folded to the inside of the section
D.sub.2.
[0041] That is, the left half part of the upper wall portion
U.sub.2 deforms to rotate clockwise in the figure around the
connecting portion UR.sub.2. Further, a right half part of the
upper wall portion U.sub.2 deforms to rotate counterclockwise in
the figure around a connecting portion UR.sub.3. In the meantime,
the left half part of the lower wall portion L.sub.2 deforms to
rotate counterclockwise in the figure around the connecting portion
LR.sub.2. Further, a right half part of the lower wall portion
L.sub.2 deforms to rotate clockwise in the figure around a
connecting portion LR.sub.3. Note that, since the upper wall
portion U.sub.2 and the lower wall portion L.sub.2 buckle to be
folded to the inside of the section D.sub.2, an uncrushed part
slightly remains in the section D.sub.2.
[0042] The section D.sub.3 is crushed in the same form as the crush
form of the section D.sub.1. That is, an upper wall portion U.sub.3
and a lower wall portion L.sub.3 buckle to project to the outside
of the section D.sub.3 (see FIG. 5A). Further, the section Da is
crushed in the same form as the crush form of the section D.sub.2.
That is, an upper wall portion U.sub.4 and a lower wall portion
L.sub.4 buckle to be folded to the inside of the section D.sub.4.
Further, the section D.sub.5 is crushed in the same form as the
crush form of the section D.sub.1. That is, an upper wall portion
U.sub.5 and a lower wall portion L.sub.5 buckle to project to the
outside of the section D.sub.5 (see FIG. 5B).
[0043] Then, the section D.sub.6 starts to be crushed. Here, the
width d.sub.6 of the section D.sub.6 (that is, the length of an
upper wall portion U.sub.6 and a lower wall portion L.sub.6 in the
application direction of the pressing load (a buckling load)) is
set to be smaller than the width d.sub.5 of the section D.sub.5 to
be crushed before the section D.sub.6. Accordingly, buckling loads
of the upper wall portion U.sub.6 and the lower wall portion
L.sub.6 are higher than buckling loads of the upper wall portion
U.sub.5 and the lower wall portion L.sub.5. In other words, the
upper wall portion U.sub.6 and the lower wall portion L.sub.6 can
be hardly affected by deformations of the upper wall portion
U.sub.5 and the lower wall portion L.sub.5. That is, a part
constituted by the sections D.sub.6 to D.sub.5 can be considered to
be separated from a part constituted by the sections D.sub.1 to
D.sub.5. Accordingly, the sections D.sub.6 to D.sub.5 are crushed
in the same forms as those of the sections D.sub.1 to D.sub.3,
respectively (see to FIGS. 5C, 5D). That is, the upper wall portion
U.sub.5 and the lower wall portion L.sub.5 deform to project to the
outside of the section D.sub.5. However, the upper wall portion
U.sub.6 and the lower wall portion L.sub.6 buckle to project to the
outside of the section D.sub.6 (see FIG. 5C) in a similar manner to
the upper wall portion U.sub.1 and the lower wall portion L.sub.1
without being affected by the deformations of the upper wall
portion U.sub.5 and the lower wall portion L.sub.5. Further, an
upper wall portion U.sub.7 and a lower wall portion L.sub.7 buckle
to be folded to the inside of the section D.sub.7. Further, an
upper wall portion U.sub.8 and a lower wall portion L.sub.8 buckle
to project to the outside of the section D.sub.8 (see FIG. 5D).
Result of Second Experiment
[0044] In the second experiment, the columnar object OB was caused
to collide, from the left side, with the central part of the impact
absorption device 1 in the vehicle front-rear direction (see FIG.
6), similarly to the first experiment. Note that, in the second
experiment, as illustrated in the figure, the object OB is slightly
inclined from the vertical direction (the vehicle height
direction), that is, the object OB is inclined such that the upper
side of the object OB is placed slightly on the right side from the
lower side of the object OB. More specifically, the inclination
angle of the object OB from the vertical direction is "5.degree.."
In the present experiment, the sections D.sub.1 to D.sub.8 were
crushed generally in the same forms as those in the first
experiment, as described below.
[0045] That is, the sections D.sub.1 to D.sub.8 were crushed in
this order. As illustrated in FIGS. 7A, 7B, the upper wall portion
U.sub.1 and the lower wall portion L.sub.1 buckle to project to the
outside of the section D.sub.1. Further, the upper wall portion
U.sub.2 and the lower wall portion L.sub.2 buckle to be folded to
the inside of the section D.sub.2. Further, the upper wall portion
U.sub.3 and the lower wall portion L.sub.3 buckle to project to the
outside of the section D.sub.3. Further, the upper wall portion
U.sub.4 and the lower wall portion L.sub.4 buckle to be folded to
the inside of the section D.sub.4. Further, the upper wall portion
U.sub.5 and the lower wall portion L.sub.5 buckle to project to the
outside of the section D.sub.5. Note that, in the present
experiment, since the object OB is inclined as described above, a
pressing load directed diagonally downward toward the right side is
applied to each section D.sub.n. On that account, the lower wall
portion L.sub.n buckles slightly earlier than the upper wall
portion U.sub.n. Hereby, as illustrated in the figures, the
sections D.sub.1 to D.sub.5 slightly tilt downward.
[0046] Subsequently, as illustrated in FIG. 7C, the upper wall
portion U.sub.6 and the lower wall portion L.sub.6 buckle to
project to the outside of the section D.sub.6. The section D.sub.6
is crushed as such, but as described above, the width d.sub.6 of
the section D.sub.6 is set to be smaller than the width d.sub.5 of
the section D.sub.5 to be crushed before the section D.sub.6.
Accordingly, buckling strengths of the upper wall portion U.sub.6
and the lower wall portion L.sub.6 are higher than buckling
strengths of the upper wall portion U.sub.5 and the lower wall
portion L.sub.5. Accordingly, a difference between a buckling speed
of the upper wall portion U.sub.6 and a buckling speed of the lower
wall portion L.sub.6 is not so large. On this account, tilting in
the section D.sub.6 is smaller than tilting in the section
D.sub.5.
[0047] As illustrated in FIGS. 7C, 7D, the upper wall portion
U.sub.7 and the lower wall portion L.sub.7 buckle to be folded to
the inside of the section D.sub.7. Further, the upper wall portion
U.sub.8 and the lower wall portion L.sub.8 buckle to project to the
outside of the section D.sub.8. As illustrated in the figures, the
sections D.sub.7, D.sub.8 also tilt slightly downward.
Effects
[0048] As described above, in these experiments, the width d.sub.6
of the section D.sub.6 placed in the intermediate part of the
impact absorption device 1 in the vehicle width direction was set
to be smaller than the width d.sub.5 of the section D.sub.5 placed
on the left side of the section D.sub.6 (on a reverse side in the
advancing direction of the object OB). Hereby, tilting of the whole
impact absorption device 1 could be set to be smaller than that of
the example in the related art illustrated in FIG. 11. Hereby, such
a situation that an uncrushed part remains in a section in the
impact absorption device 1 could be prevented differently from the
example in the related art, and an absorption amount of a collision
energy in the first experiment and an absorption amount of a
collision energy in the second experiment could be set to the same
level. That is, as illustrated in FIG. 8, the change characteristic
of a pressing load to an entry amount of the object OB (a
compression stroke of the impact absorption device 1) in the second
experiment is generally the same as the change characteristic in
the first experiment.
[0049] That is, with the impact absorption device 1, even in a case
where the object OB collides (advances) in a direction slightly
inclined from the arrangement direction of the sections D.sub.1 to
D.sub.8 of the impact absorption device 1 (e.g., in a case where a
vehicle having a relatively low vehicle height collides with a side
part of a vehicle having a relatively high vehicle height), a
collision energy can be absorbed sufficiently (see FIG. 9).
[0050] Further, as described above, the width d.sub.1 of the
section D.sub.1 (that is, the length of the upper wall portion
U.sub.1 and the lower wall portion L.sub.1 in a buckling-load
direction) is set to be relatively small, so that a buckling load
in the section D.sub.1 is relatively high. That is, as illustrated
in FIG. 8, a pressing load to be applied to the impact absorption
device 1 rises steeply at an initial stage just after the object OB
collides with the impact absorption device 1. Note that a peak of
the pressing load does not exceed an allowable load.
[0051] Note that, at the initial stage, the upper wall portions
U.sub.2 to U.sub.8 and the lower wall portions L.sub.2 to L.sub.8
do not buckle. As described above, the abutment part between the
object OB and the rib R.sub.1 is linear, and a load concentrates on
the abutment part. However, in parts placed on the right side of
the abutment part (particularly, the upper wall portions U.sub.4 to
U.sub.8 and the lower wall portions L.sub.4 to L.sub.8), the
pressing load disperses in the vehicle front-rear direction in
those parts. Accordingly, even if the widths d.sub.n of the parts
are large to some extent, the parts do not buckle. After that, as
described above, the sections D.sub.2 to D.sub.8 are crushed in
this order. However, in the course of crushing, the pressing load
applied to the impact absorption device 1 does not exceed a
predetermined allowable load. That is, in the course from a
deformation start of the section D.sub.1 to a deformation end of
the section D.sub.8, a state where a pressing load that was high to
some extent was applied to the impact absorption device 1 could be
maintained.
[0052] Further, in an impact absorption device 1A in the related
art as illustrated in FIG. 11, an upper wall portion U.sub.n+1 and
a lower wall portion L.sub.n+1 of a section D.sub.n+1 are affected
by deformations of the upper wall portion U.sub.n and the lower
wall portion L.sub.n of the section D.sub.n provided before the
section D.sub.n+1. That is, the upper wall portion U.sub.n=2m-1 and
the lower wall portion L.sub.n=2m-1 in the section D.sub.n=2m-1
(the sections D.sub.1, D.sub.3, D.sub.5, D.sub.7) buckle to project
to the outside of the section D.sub.n=2m-1. In the meantime, the
upper wall portion U.sub.n=2m and the lower wall portion L.sub.n=2m
in the section D.sub.n=2m (the sections D.sub.2, D.sub.4, D.sub.6,
D.sub.8) buckle to be folded to the inside of the section
D.sub.n=2m.
[0053] On the other hand, in the impact absorption device 1 of the
present embodiment, the width d.sub.6 of the section D.sub.6 is set
to be smaller than the width d.sub.5 of the section D.sub.5 to be
crushed before the section D.sub.6, so that the upper wall portion
U.sub.6 and the lower wall portion L.sub.6 can be hardly affected
by deformations of the upper wall portion U.sub.5 and the lower
wall portion L.sub.5. Hereby, the upper wall portion U.sub.6 and
the lower wall portion L.sub.6 can buckle to project to the outside
of the section D.sub.6. Then, the upper wall portion U.sub.7 and
the lower wall portion L.sub.7 of the section D.sub.7 are affected
by the upper wall portion U.sub.6 and the lower wall portion
L.sub.6 of the section D.sub.6, so that the upper wall portion
U.sub.7 and the lower wall portion L.sub.7 buckle to be folded to
the inside of the section D.sub.7. Further, the upper wall portion
U.sub.8 and the lower wall portion L.sub.8 of the section D.sub.8
are affected by the upper wall portion U.sub.7 and the lower wall
portion L.sub.7 of the section D.sub.7, so that the upper wall
portion U.sub.8 and the lower wall portion L.sub.8 buckle to
project to the outside of the section D.sub.8.
[0054] As described above, in the case of the impact absorption
device 1A, when the section D.sub.8 is crushed, the upper wall
portion U.sub.8 and the lower wall portion L.sub.8 buckle to the
inside of the section D.sub.8, so that the upper wall portion
U.sub.8 and the lower wall portion L.sub.8 are sandwiched between
the rib R.sub.8 and the rib R.sub.9. On the other hand, in the case
of the impact absorption device 1, when the section D.sub.8 is
crushed, the upper wall portion U.sub.8 and the lower wall portion
L.sub.8 buckle to the outside of the section D.sub.8, so that the
upper wall portion U.sub.8 and the lower wall portion L.sub.8 are
not sandwiched between the rib R.sub.8 and the rib R.sub.9.
Accordingly, a compression stroke in the section D.sub.8 of the
impact absorption device 1 is larger than a compression stroke in
the section D.sub.8 of the impact absorption device 1A.
Accordingly, collision-energy absorption performance of the impact
absorption device 1 is higher than that of the impact absorption
device 1A.
[0055] As described above, by generally optimizing the number of
ribs R.sub.n and intervals therebetween (the number of sections
D.sub.n and the width d.sub.n), the impact absorption device 1
reduced in weight and having improved collision-energy absorption
performance can be achieved.
[0056] Further, the present disclosure is not limited to the above
embodiment, and various alterations can be made within a range that
does not deviate from the object of the present disclosure.
[0057] For example, in the above embodiment, the upper wall portion
U and the lower wall portion L are placed in parallel to each
other. However, for example, as illustrated in FIG. 10, the upper
wall portion U may be inclined such that the left end of the upper
wall portion U is placed below the right end of the upper wall
portion U, and the lower wall portion L may be inclined such that
the left end of the lower wall portion L is placed above the right
end of the lower wall portion L. That is, a distance, in the
vehicle height direction, of the left end of the upper wall portion
U and the left end of the lower wall portion L may be set to be
smaller than a distance, in the vehicle height direction, of the
right end of the upper wall portion U and the right end of the
lower wall portion L. In this configuration, in a case where the
object OB collides with the impact absorption device 1 in a state
where the object OB is slightly inclined to the arrangement
direction of the sections D.sub.1 to D.sub.8 like the second
experiment, for example, an angular difference between the
application direction of a load to the lower wall portion L and the
inclination direction of the lower wall portion L is relatively
small, so that tilting of the impact absorption device 1 can be
easily restrained.
[0058] Further, the number of sections in the impact absorption
device 1 is not limited to the above embodiment, for example. Note
that it is preferable that the width d.sub.n of one section D.sub.n
placed in the intermediate part in the arrangement direction of the
sections be set to be smaller than a width d.sub.n-1 and a width
d.sub.n+1 of a section D.sub.n-1 and a section D.sub.n+1,
adjacently provided on both sides of the one section D.sub.n, and
the number of sections placed on the right side (in the advancing
direction of the object OB) relative to the rib R.sub.n
constituting the one section D.sub.n in the intermediate part be
set to an odd number. In this configuration, the upper wall portion
and the lower wall portion constituting a last section to be
crushed buckle to project to the outside of the last section.
Hereby, in comparison with a case where the upper wall portion and
the lower wall portion constituting the last section to be crushed
buckle to be folded to the inside of the last section, a large
compression stroke can be achieved, so that collision-energy
absorption performance can be set to be high.
[0059] Further, the width d.sub.6 of the section D.sub.6 that is a
central section among three consecutive sections D.sub.5, D.sub.6,
D.sub.7 in the impact absorption device 1 in the above embodiment
is smaller than the width d.sub.5 of the section D.sub.5 and the
width d.sub.7 of the section D.sub.7, the section D.sub.5 and the
section D.sub.7 being adjacently placed on both sides of the
section D.sub.6. The impact absorption device 1 includes a set part
D.sub.5-D.sub.6-D.sub.7 constituted by the three consecutive
sections as described above, but the impact absorption device 1 may
include a plurality of set parts D.sub.5-D.sub.6-D.sub.7. Further,
the central section D.sub.6 in the part D.sub.5-D.sub.6-D.sub.7 may
be divided into a plurality of sections.
[0060] In an aspect of the present disclosure, an interval between
ribs constituting one given section in a part adjacently placed on
either side of the three consecutive sections among the sections
may be equal to or more than an interval between ribs constituting
an adjacent section adjacently placed on a reverse side of the one
given section in the advancing direction of the object.
[0061] Further, in the aspect of the present disclosure, the number
of sections placed on a forward side, in the advancing direction of
the object, from a rib placed on the reverse side in the advancing
direction of the object out of two ribs constituting the central
section may be an odd number.
[0062] Further, in the aspect of the present disclosure, the upper
wall portion and the lower wall portion may be placed in parallel
to each other.
[0063] Further, in the aspect of the present disclosure, an
interval, in the vehicle height direction, between first end parts
of the upper wall portion and the lower wall portion may be smaller
than an interval, in the vehicle height direction, between second
end parts of the upper wall portion and the lower wall portion, the
first end parts being placed on the reverse side in the advancing
direction of the object, the second end parts being placed on the
forward side in the advancing direction of the object.
[0064] In the impact absorption device according to the aspect of
the present disclosure, a width (the interval between the ribs
constituting the central section) of a part (hereinafter referred
to as a first part) of each of the upper wall portion and the lower
wall portion, the part constituting the central section, is smaller
than a width of a part (hereinafter referred to as a second part)
of each of the upper wall portion and the lower wall portion, the
part constituting a section adjacently placed on either side of the
central section. Accordingly, a buckling strength of the first part
is higher than a buckling strength of the second part. Accordingly,
even if the object collides with the vehicle in a state where the
object is slightly inclined from the arrangement direction of the
sections, a difference between a buckling speed of the upper wall
portion in the first part and a buckling speed of the lower wall
portion in the first part is not so large. On this account, tilting
in the central section is smaller than tilting in the sections
adjacently provided on both sides of the central section. As such,
with the impact absorption device of the present disclosure,
tilting in the central section is relatively small. In the example
illustrated in FIG. 12, tilting caused in each section is
accumulated, and an uncrushed part remains in a last section.
However, in the impact absorption device of the present disclosure,
tilting in a section crushed earlier than the central section can
hardly affect the central section and sections subsequent to the
central section, thereby making it possible to restrain an
uncrushed part illustrated in the example of FIG. 7. Accordingly,
the present disclosure can provide an impact absorption device
having improved collision-energy absorption performance.
* * * * *